Checking and control arrangement for facsimile telegraph apparatus



Jan. 19, 1954 CANNON ETAL 2,666,821

CHECKING AND CONTROL ARRANGEMENT FOR FACSIMILE TELEGRAPH APPARATUS Filed Feb. 1, 1952 Patented Jan. 19, 1954 CHECKING AND CONTROL ARRANGEMENT FOR FACSIMILE TELEGRAPH APPARATUS Frank Herbert Cannon, Chatswood, New South Wales, Australia, and Alan Arthur Kirchel, Beckenham, England, assignors to Muirhead & Company Limited, Elmers End, Beckenham,

England Application February 1, 1952, Serial No. 269,502

Claims priority, application Great Britain February 2, 1951 r 4 Claims. (Cl. 200-33) This invention relates to checking and control arrangements for facsimile telegraph apparatus, suitable for use in automatic facsimile telegraph systems in which the receiving machine is required to operate without manual control.

To ensure that a message is received, it is necessary that both before and after the actual transmission of the message, the receiving machine is automatically checked to see that it is functioning correctly in every way, and if this is not so, to operate a failure alarm at the transmitting machine Where manual operation is provided.

Among various provisions that are necessary on the receiving machine are the following examples:

(a) The driving motor, upon starting, must be allowed to attain full speed, before any phasing or synchronising controls are applied;

(b) The phasing or synchronising operation must be allowed to take place before any message information is transmitted;

(c) If conditions (a) and (b) are not completed within their proper time, it is necessary to inform the transmitter of a fault condition.

((1) If at the completion of transmission, and end of message signal is not correctly received, then the receiver must close itself down, and send a fault condition signal to the transmitter.

An object of the present invention is the provision of a suitable mechanism by which the automatic checking and control of the receiver can be effected.

The invention consists of a checking and control arrangement for facsimile telegraph a paratus in which a spring-restored disc is adapted to be rotated from its normal position by the driving motion of the apparatus in order to effeet a series of contact operations and when it reaches an extreme position is released for restoration to its normal position.

The timing disc is employed to time certain operations at the receiver and in the event of the sequence of the supervisory signals being interrupted due to afault condition, to take control. Under fault conditions the timing disc effects the close-down of the receiver and in conjunction with certain guard circuits of the transmitter causes a failure alarm to be operated I at the transmitter.

Preferably the disc is released by axial movement thereof.

Conveniently the disc is rotated in a step-bystep manner.

An embodiment of the invention is shown in the accompanying drawings.

Figure 1 is a diagram of the general arrangement.

Figure 2 shows the driving mechanism.

Figure 3 shows the resetting mechanism.

In the embodiment the checking and control arrangement consists of a timing disc I mounted in bearings 2 in such a way to allow some axial movement. The disc is held in its normal position, rotationally, by a return spring 3, against a stop block 4, and axially by a leaf spring 5 against a reset magnet armature 6. Around the outside rim of the disc are cut ratchet teeth I (Figure 2) which are engaged by a feed pawl 8 and a retaining pawl 9. The feed pawl is operated by a cam 10 which is, in turn, geared to the recording scroll l I, so that upon the rotation of the scroll the timing disc will be fed tooth by tooth.

On the same side as the ratchet teeth, but nearer to the centre of the disc, is a number of ridges I2 co-operating through plungers I 3 with associated spring contact sets 14 (only one shown) so that the contacts are held normally in an unoperated position. The ridges are cut into arcs of predetermined length so that when the disc is revolved the plungers fall 01f the ends of ridges, allowing the operation of the contact sets at their appropriate times.

A supervisory spring contact set (not shown) is operated by a small projection Ia on the disc so that the contact is made only for a short time.

A restoring spring contact set (not shown) is operated by a ramp (not shown) when the timing disc is fed to its extreme position, i. e. just less than 360. Normally before this contact set operates, the timing disc is reset by operation of the reset magnet 15 (Figure 1).

When the reset magnet 15 operates, its armature 6 pushes the timing disc l sideways against the leaf spring 5 and in so doing, the ratchet teeth I disengage from the pawls 8 and 9, and the ridges [2 move away from the plungers it so that the disc is free to reset to its starting position. A reset magnet contact I6 (Figure 3) is provided in circuit with the release magnet, so that the current to the magnet is switched off when the timing disc is fully reset; allowing the disc to engage the ratchet pawls and contact plungers.

When the timing disc 4 is reset and returns to its start position, it is stopped by a pin l1 striking the stop block 4. In order to reduce the bounce of the disc to something less than the pitch of one ratchet tooth, a relatively heavy damping ring it is held against the side of the disc by a spring is. Hence, as the pin l'l strikes the stop block 5 the timing disc tends to bounce back, While the damping ring 18 continues in the same direction; due to its friction against the side of the timing disc, the damping ring exerts a heavy torque against the bounce .of the timing disc, to such an extent that the bounce is, for practical purposes, eliminated.

The contact sets M are provided to initiate the various functions set out in provisions (a) to (d) and their operation is as follows:

When the receiver is required to operate, the driving motor as (Figure 2) geared to the recording scroll H is energised and the scroll revolves, feeding the timing disc I. When sunficient time has elapsed to enable the motor to attain full speed, contacts of the set it Will operate to switch in the phasing mechanism. After time to allow the phasing operation to be completed, further contacts of the set 54 will operate to prepare for the message intelligence to be received. Should at this time the receiver not be in a correct mechanical condition, the supervisory contact set operates the supervisory controls, and allows still further contacts of the set M which operate immediately after the supervisory contact set to operate a failure alarm at the transmitter, and stop the receiver motor.

11?, however, a fault occurs during the transmission of the actual message the still further contact set will be ineffective and the end of message signal from transmitter will not be correctly received, to reset the timing disc and stop the receiver. In this event the receiver continues to operate until the timing disc is fed past its normal end of message position and operates the restoring contact set. This contact will 0perate the failure alarm at the transmitter, stop the receiver motor and cause the reset magnet to operate, to reset the timing disc.

Various modifications may be made within the scope of the invention.

We claim:

1. A checking and control arrangement for facsimile telegraph apparatus comprising a timing disc mounted in hearings in such a Way as to allow some axial movement and having ratchet teeth therearound, a return spring for holding the disc in its normal position, rotationally,

against a stop, a spring for holding the disc in one axial position, a feed pawl and retaining pawl for rotating the disc, contact set adapted to be operated by the disc at various positions in its rotation, and means for pushing the disc sideways against said spring to disengage the ratchet teeth from the pavvls so that the disc is free to reset to said normal position.

2. A checking and control arrangement for facsimile telegraph apparatus comprising a timing disc mounted in hearings in such a way as to allow some axial movement and having ridges in the form of arcs of predetermined length formed thereon, spring contact sets (ac-operating through plungers with the ridges, means for driving the disc rotationally from a normal position, means for pushing the disc sideways to release it from said driving means and spring contact sets, and means for thereupon restoring the disc to said normal position.

3. A checking and "control arrangement for facsimile telegraph apparatus comprising a timing disc mounted in bearings, a stop, spring means for holding the disc in its normal position against the stop, means for driving the disc rotationally from its normal position, means for releasing the disc to be restored by said spring means to its normal position, and a damping ring held against the side of the disc by spring IE6"- sure for the purpose of eliminating bounce when the disc reaches its normal position against the stop.

4. A checking and control arrangement for facsimile telegraph apparatus comprising a timing disc having ridges in the form of arcs of predetermined length formed thereon, spring contact sets co-operating through plungers with the ridges, means for driving the disc rotationally from a normal position, means for releasing the disc from the driving means and the contact sets,

and means for thereupon restoring the disc to said normal position.

FRANK HERBERT CANNON. ALAN ARTHUR KIRCHEL.

References Cited in the file of this patent FOREIGN PATENTS Number Country .Date

716,856 Germany Jan. 31, 1942 

